vim-patch:8.2.0590: no 'backspace' value allows ignoring the insertion point

Problem:    No 'backspace' value allows ignoring the insertion point.
Solution:   Add the "nostop" and 3 values. (Christian Brabandt, closes vim/vim#5940)
aa0489e12d

runtime/doc/options.txt

@@ -734,6 +734,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	eol	allow backspacing over line breaks (join lines)
 	start	allow backspacing over the start of insert; CTRL-W and CTRL-U
 		stop once at the start of insert.
+	nostop	like start, except CTRL-W and CTRL-U do not stop at the start of
+		insert.
 
 	When the value is empty, Vi compatible backspacing is used.
 
@@ -742,6 +744,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  0	same as ":set backspace=" (Vi compatible)
 	  1	same as ":set backspace=indent,eol"
 	  2	same as ":set backspace=indent,eol,start"
+	  3	same as ":set backspace=indent,eol,nostop"
 
 				*'backup'* *'bk'* *'nobackup'* *'nobk'*
 'backup' 'bk'		boolean	(default off)

src/nvim/edit.c

@@ -8282,8 +8282,9 @@ static bool ins_bs(int c, int mode, int *inserted_space_p)
         }
       } while (revins_on
                || (curwin->w_cursor.col > mincol
-                   && (curwin->w_cursor.lnum != Insstart_orig.lnum
+                   && (can_bs(BS_NOSTOP)
-                       || curwin->w_cursor.col != Insstart_orig.col)));
+                       || (curwin->w_cursor.lnum != Insstart_orig.lnum
+                           || curwin->w_cursor.col != Insstart_orig.col))));
     }
     did_backspace = true;
   }

src/nvim/option.c

@@ -306,7 +306,7 @@ static char *(p_buftype_values[]) =   { "nofile", "nowrite", "quickfix",
 
 static char *(p_bufhidden_values[]) = { "hide", "unload", "delete",
                                         "wipe", NULL };
-static char *(p_bs_values[]) =        { "indent", "eol", "start", NULL };
+static char *(p_bs_values[]) = { "indent", "eol", "start", "nostop", NULL };
 static char *(p_fdm_values[]) =       { "manual", "expr", "marker", "indent",
                                         "syntax",  "diff", NULL };
 static char *(p_fcl_values[]) =       { "all", NULL };
@@ -1366,6 +1366,10 @@ int do_set(
                   *(char_u **)varp = vim_strsave(
                       (char_u *)"indent,eol,start");
                   break;
+                case 3:
+                  *(char_u **)varp = vim_strsave(
+                      (char_u *)"indent,eol,nostop");
+                  break;
                 }
                 xfree(oldval);
                 if (origval == oldval) {
@@ -2939,7 +2943,7 @@ ambw_end:
     }
   } else if (varp == &p_bs) {  // 'backspace'
     if (ascii_isdigit(*p_bs)) {
-      if (*p_bs >'2' || p_bs[1] != NUL) {
+      if (*p_bs > '3' || p_bs[1] != NUL) {
         errmsg = e_invarg;
       }
     } else if (check_opt_strings(p_bs, p_bs_values, true) != OK) {
@@ -6801,15 +6805,15 @@ static int check_opt_wim(void)
 }
 
 /// Check if backspacing over something is allowed.
-/// The parameter what is one of the following: whatBS_INDENT, BS_EOL
+/// @param  what  BS_INDENT, BS_EOL, BS_START, or BS_NOSTOP
-/// or BS_START
 bool can_bs(int what)
 {
   if (what == BS_START && bt_prompt(curbuf)) {
     return false;
   }
   switch (*p_bs) {
-    case '2':       return true;
+    case '3':       return true;
+    case '2':       return what != BS_NOSTOP;
     case '1':       return what != BS_START;
     case '0':       return false;
   }

src/nvim/option_defs.h

@@ -282,9 +282,14 @@ enum {
 #define WIM_BUFLASTUSED 8
 
 // arguments for can_bs()
+// each defined char should be unique over all values
+// except for BS_START, that intentionally also matches BS_NOSTOP
+// because BS_NOSTOP behaves exactly the same except it
+// does not stop at the start of the insert point
 #define BS_INDENT       'i'     // "Indent"
-#define BS_EOL          'o'     // "eOl"
+#define BS_EOL          'l'     // "eoL"
 #define BS_START        's'     // "Start"
+#define BS_NOSTOP       'p'     // "nostoP
 
 #define LISPWORD_VALUE \
   "defun,define,defmacro,set!,lambda,if,case,let,flet,let*,letrec,do,do*,define-syntax,let-syntax,letrec-syntax,destructuring-bind,defpackage,defparameter,defstruct,deftype,defvar,do-all-symbols,do-external-symbols,do-symbols,dolist,dotimes,ecase,etypecase,eval-when,labels,macrolet,multiple-value-bind,multiple-value-call,multiple-value-prog1,multiple-value-setq,prog1,progv,typecase,unless,unwind-protect,when,with-input-from-string,with-open-file,with-open-stream,with-output-to-string,with-package-iterator,define-condition,handler-bind,handler-case,restart-bind,restart-case,with-simple-restart,store-value,use-value,muffle-warning,abort,continue,with-slots,with-slots*,with-accessors,with-accessors*,defclass,defmethod,print-unreadable-object"

src/nvim/testdir/test_backspace_opt.vim

@@ -19,6 +19,8 @@ func Test_backspace_option()
   call assert_equal('eol', &backspace)
   set backspace=start
   call assert_equal('start', &backspace)
+  set backspace=nostop
+  call assert_equal('nostop', &backspace)
   " Add the value
   set backspace=
   set backspace=indent
@@ -27,7 +29,11 @@ func Test_backspace_option()
   call assert_equal('indent,eol', &backspace)
   set backspace+=start
   call assert_equal('indent,eol,start', &backspace)
+  set backspace+=nostop
+  call assert_equal('indent,eol,start,nostop', &backspace)
   " Delete the value
+  set backspace-=nostop
+  call assert_equal('indent,eol,start', &backspace)
   set backspace-=indent
   call assert_equal('eol,start', &backspace)
   set backspace-=start
@@ -47,7 +53,9 @@ func Test_backspace_option()
   call assert_equal('1', &backspace)
   set backspace=2
   call assert_equal('2', &backspace)
-  call assert_false(match(Exec('set backspace=3'), '.*E474'))
+  set backspace=3
+  call assert_equal('3', &backspace)
+  call assert_false(match(Exec('set backspace=4'), '.*E474'))
   call assert_false(match(Exec('set backspace=10'), '.*E474'))
 
   " Cleared when 'compatible' is set
@@ -101,6 +109,39 @@ func Test_backspace_ctrl_u()
         \ "8 this shouldn't be deleted (not touched yet) vim7",
         \ ""], getline(1, '$'))
 
+  " Reset values
+  set compatible&vim
+  set visualbell&vim
+  set backspace&vim
+
+  " Test new nostop option
+  %d_
+  let expected = "foo bar foobar"
+  call setline(1, expected)
+  call cursor(1, 8)
+  exe ":norm! ianotherone\<c-u>"
+  call assert_equal(expected, getline(1))
+  call cursor(1, 8)
+  exe ":norm! ianothertwo\<c-w>"
+  call assert_equal(expected, getline(1))
+
+  let content = getline(1)
+  for value in ['indent,nostop', 'eol,nostop', 'indent,eol,nostop', 'indent,eol,start,nostop']
+    exe ":set bs=".. value
+    %d _
+    call setline(1, content)
+    let expected = " foobar"
+    call cursor(1, 8)
+    exe ":norm! ianotherone\<c-u>"
+    call assert_equal(expected, getline(1), 'CTRL-U backspace value: '.. &bs)
+    let expected = "foo  foobar"
+    call setline(1, content)
+    call cursor(1, 8)
+    exe ":norm! ianothertwo\<c-w>"
+    call assert_equal(expected, getline(1), 'CTRL-W backspace value: '.. &bs)
+  endfor
+
+  " Reset options
   set compatible&vim
   set visualbell&vim
   set backspace&vim